| OVERVIEW |
General information : Monthly mean sea surface Chlorophyll-a concentration in mg.m-3 derived from the SeaWiFS sensor.
Processing information : Chlorophyll-a data is reprocessed (V5.1) by the Goddard Space Flight Centre (NASA) using SeaDAS 4.8 and the standard OC4-V4 algorithm for chla.Temporal characteristics: This dataset comprises of standard mapped image monthly mean global sea surface chlorophyll-a maps at 0.125° resolution (L3 product).
Temporal characteristics: This dataset comprises of standard mapped image monthly mean sea surface chlorophyll-a maps at 2km resolution (L3 product).
Description of observation methods/instruments : The remote sensing of 'Ocean Colour' represents a measure of the spectral variations in the light leaving the water surface, subsequently interpreted in terms of concentrations of optically-significant constituents in the water. The electromagnetic signal collected by the sensor on-board the satellite is largely determined by photons that have never reached the water surface, but have been backscattered within the atmosphere through multiple interactions between gas molecules and aerosols. After removing the atmospheric contribution, the water leaving radiance recorded at a given time by the satellite reflects the optical properties of the water which, in turn, mirrors a specific structure and biogeochemical composition of the marine waters. Accordingly, the satellite-derived reflectance at the air-sea interface can be related to the concentration of an optically-significant constituent (e.g. chlorophyll). The retrieval of chlorophyll from SeaWiFS for case 1 waters (optically dominated by phytoplankton and associated products) uses a 4th order (O'Reilly et al. 2000).
Quality/accuracy/calibration information :The 'standard' algorithm proposed by space agencies to process data from their sensors has a nominal accuracy of ~35% in the retrieval of surface chlorophyll in case 1 waters.
Suitability : Satellite Ocean colour imagery is the only source of biological information routinely available on a global basis and is thus one of the few sources of information that can be used to validate phytoplankton distributions predicted by regional to global-scale numerical models. To improve the forecasting ability of oceans simulations, satellite-derived chlorophyll fields can be directly assimilated into numerical models using data insertion and adjoint methods.
This product is available in different regional subsets:
- Baltic subset: 3.5E to 30.5E, 52.75N to 66.0N
- North Atlantic Drift subset: -40.0E to 12.5E, 35.0N to 65.0N
- Mediterranean subset: -6.0E to 36.5E, 30.0N to 46.0N
- North-East Atlantic Subtropical Gyre subset: -40.0E to -5.0E, 10.0N to 45.0N
- Atlantic Sub-Arctic subset: -40.0E to 40.0E, 55.0N to 80.0N
Expected type of users : The product is suitable for studies of ecosystem dynamics and biogeochemical cycles. It is also designed for assimilation into models operated by the Mersea forecasting TEPs as these users need products with appropriate documentation and assessed uncertainties.
References :- O'Reilly, J.E. and co-authors, 2000: "Ocean color chlorophyll a algorithms for SeaWiFS, OC2, and OC4: Version 4." In: J.E. O'Reilly and co-authors, SeaWiFS Postlaunch Calibration and Validation Analyses, Part 3. NASA Tech. Memo. 2000-206892, Vol. 11, S.B. Hooker and E.R. Firestone, Eds., NASA Goddard Space Flight Center, Greenbelt, Maryland, 9-23.
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| PARAMETERS GROUP |
| (from BODC) |
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| PARAMETERS
(parameter, unit, convention)
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- concentration_of_chlorophyll_in_sea_water,kg m-3,CF
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